Telephone system



Sept. l5, 1925. 1,554,111 T. G. MARTIN TELEPHONE SYSTEM Filed Sept. 16, 1905 4 Sheets-Sheet 1 w QI N2? W i2 sep;- 15, 1925. T. G. MARTIN TELEPHONE SYSTEMv Filed sept; 16, .1905

4v Sheets-Sheet `:5

scpf. 15, 1925. Y `1,554,111

T. G. MARTIN TELEPHONE SYSTEM Filed sept. 1e, 1905 4 sheets-sheet 4 @M gf @Maf Patented Sept. 15, 1925.

YUNITED STATES PATENT `OFFICE.

j TALBOT G. MARTIN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESN ASSIGNMENT TO AUTOMATIC ELECTRIC COMPANY, ACORPORAT`ION 0F ILLINOIS.

TELEPHONE SYSTEM.

Application filed September To all 1li/tom t may concern.'

Be it known that I, TALBOT G. MARTIN, a citizen of the United States of America, and resident of Chicago, Cook County, Illinois, have invented a certain new and useful Improvement in Telephone Systems, of which the following is a specification.

My inventionrelates to telephone systems and more particularly to telephone systems in which means are provided for enabling the .calling subscriber to establish connection with the called subscribers line without the assistance of a switchboard operator, although in this particular case, more specilically considered, it contemplates certain improvements whereby a subscriber of an 'automatic telephone exchange may use his calling device for obtaining connection automatically with theline of a subscriber of a manual exchange, and may then signal the called subscriber in the usual way. My invention also relates to automatic telephone apparatus and systems `in which the .current both for talking and switching and signaling purposes is all supplied. from the exchange or central station, as, for example, by means of batteries from which the talking and switching current is derived, and ringinggenerators from which the current is ob tained for ringing. the vbells at the subscribers stations. In this respect, my invention is in the nature of an improvement on the common battery automatic telephone system disclosed in my prior application, Serial No. 258,508, tiled May 2, 1905'. Still more specifically considered, my invention contemplates certain improvements in automatic telephone switching` apparatuswhereby a subscriber of the common battery auto- Y matic telephone system may establish connection with the line of a manual switchboard exchange of a panticular `type lor character, as will hereinafter more fully appear. 1

To the foregoing and otheruseful ends, my invention consists in matters hereinafter set forth and claimed.

In the accompanying drawings, Figurel is a diagram of a cord-circuit A, and of two sub-stations #620 and #300 of a manual system, of a type in connection with which I have elected to illustrate my invention.

Figs.` 1 and 2 taken together illustrate dia.- grammatically the switches and apparatus brought into play when an automatic sub- 16, 1905. Serial No. 278,816.

scriber :ft/:220 is connected with a manual subscriber #620, a first-selector being represented at C to the left of line X-X, and it connector at D to the right of the same ine.

F 3 is a perspective diagram of the Erst-selector?7 C, and Fig. 4: of the connector?9 D.

Referring to Fig. 1, thesub-station #620, like all other sub-stations of the manual system to which said station belongs, is provided with a ringer 2 and a condenser 3 in the ringing-circuit, and with a transmitter lland a receiver 5 in the talking-circuit, and a retardation-coil 6 in the battery-circuit. Each subscribers line terminates in the armatures of a cut-off-relay, asdo the line-conductors l0 and l1 of the above substation #620 whichl terminates in the cut-offrelay-armatures y12 and 13. In order lto make clear the construction of the cord-circuit A, it will be best to follow .the steps of the manual subscriber atsub-station #300 while he obtains connection with the manual sub-station #620; In Vmalizingtlie call, the

subscriber at the former station'removes his receiver 14 `from the switch-hook 15 and thereby connects the two-contact-points 16 and 17 with said hook when it rises. At once the line-lamp 18 becomes illuminated as the direct result of the energizing of the line-relay19, by acurrent that iiowsfrom ground-terminal G through the armature 20 and the line-conductor 2l, through the retardation-coil 22 and the switch-hook 15, thetransmitter 23, the line-conductor 24, then through the armature 25, conductor 2G, line-relay'19 and conductor 27 to the nongrounded terminal of the battery B. iVhen the armature 28`of said line-relay is attractecha circuit is closed from thebattery B, throughy the line-lamp 18 and the ground. terminal Gl, `by way of a contact-point 29 and thearmature 28.1 The manual operator then inserts the answering -plug30 into the jack 31, and thereby closes another energizing circuit through the cut-oif-relay 8,`from the ground-terminal G2, through the cut-offrelayl 8, the conductor 32 and jack-sleeve 33, conductor 34andsupervisory-relay 35, thence` to the non-grounded terminal ofthe battery B to the grounded terminal G3. Then the cut-off -relay attracts its armatures, the circuit through Vthe line-coil v19 is opened at the point 36, and when the armature' 28 falls away rom the contact-point V29, the energizing circuit "through the lamp 18 is also broken and the light is extinguished. At the same time that the cut-of-,relay is energized, thesupervisory-relay 35, being in series with the former, is also energized. As soon as the cut-of-relay-armatures 20-and 25 close with the contact-points 37 and 38, respectively, a second supervisory-relay 39 is energized by a current that passes from the mon-grounded terminal of the battery B throught-he supervisory-relay35,1conductors 34 Vand 32, armature 25, conductor 24, I'the transmitter 23 of 4lthe' sub-station #300, switch-hook 15, retardation-coil 22, conductor 21, armature 20, contact-point 37, conductor 41, and tip-.spring "42Vof 2jack31, thence through conductor 7 and supervisoryrelay 39 tothe grounded ',termin'al'Gr3 of the battery 1B. The two 'supervisory-relaysithus energizedwill remain so asflong asthe substation v#s300 4is -in electrical 'connection with the lcord-circuit A. The central operator then, by means of a cam, throws thecamsprings l'43 and 44 into .contact .with =the contact-points 45 and E46, respectively, thereby placingthereceiver47 across the calling subscriber?s .line iby Lmeans of the `conductor 48 on one iside, and -the conductor 49 on the other. lThe.operatoru/villthen speakain the transmitter v50 and inquire of the callingv subscriber lthe number desired. The number 620being-given,ftl're operator will rst test the eline y#620fbystrilri-ng.; the'sleeve 51 of the jack 52"with the tip 53 ofthe plug l54.-.

Htheline do'es not test ibusyiin a'm'anner that will be hereinafter described, the operator willinsert said pluginfth'e 'jack -5,2. As soon as thisiis done, the cut-o relay isfenergized by a current that passes from the non-'grounded terminal of the battery B1 to the.-ground+terminal^Gr*, through'the cutoff-relay 55 Y conductor "56', jack-sleeve `51, conta c't-point 58,. conductor 59, 'snpervisoryrelay to theynon-g'rounded terminal 'of the battery B1. The supervisory-relay ybeing y in series with the. cut-otf-relay 55, the armatures of the lorinerarey attracted/and the contacts 61 and 62 areldrawn against the contactpoints 63 'and (h-respectively. As soon as the cut-of-relay 55-is energized, the rarmatures 12 'and 13: are'fd'rawn linto conta-'et with the contact-points 66 and 67, respectively, andthe called subseribers line-islthen extended to the jack 52 through the armatures 12 and and' the eontact-points' and 67 'with which the kformer larefengaged. "The manual-boardoperator will-then, by means ofalreyfpress'the springs 68'and {S9-against the contact-points V and 171, respectively. Ringing-current will itl-ien be sent fthrough the ringing apparatus of the sub-station #620 from fthe .ringing-generator .1R ithrough l#the contact-point 7 0,l the springend thel `plugtip53,eonducto`r7 2, contact-point 67, armature 13, conductor 11, condenser 3, switchhookV 73, ringer l2, thence through the lineconductor 10, armature 12, contact-point 66, Vconductor 56, jack-sleeve 51, spring 69 and contact-point 71, retardation-coil 74, conductor 7 5a, through the battery B1 to the `grounded terminal G3, to ground G5 and back to the ringing-generator R. The subscriber at sub-station #620, upon hearing the bell ring, will answer by removing his receiver 5 from the switch-hook 73, which latter on rising places the contact-points and 7,6 inelectrical connection. As soon as the said points are connected, and after the operator restores the springs .68 and. 69 to their normal position .against `the contactpoints 58 and 77, battery-current for talking `'purposes passesthrough the called subscribers Ytransmitter' from 1 the non-grounded terminal of battery B1, through the supervisory-relay'60, conductor 59, contact-point 58, :spring 69, .jack-sleeve 51, yconductor 56, armature 12,'conductor `10 yand transmitter 4, throughthe switch-110011673, retardationcoil 6 and 'conductor 11, thence through the armature 13, conductor 72, jack-tip-spring 78, spring68, contact-.point 77, conductors 79, -62 and 80, supervisory-relay 81 to the grounded terminalGr3 of battery B1. The subscriber `#30() being now connected with the subscriber #620, the voice-currents will travel back and forth over the following circuit: from the transmitter 4 of the .substation,#620, over the conductor 10, through varmature 12, the jack-sleeve 51 and Vspring '69, 'conductor 59 Vand condenser 82, thef'conductor 34,jfacksleeve33, and then over the conductors 32 and k24, i through the transmitter 23 of sub-station l#300, the switch-hook 15,receiverf14, conductors 21 and y41, thence through the tip-spring 42, the conductor .7, condenser 83, conductors- 80,62'and 79, con.- tact-point 7 7 spring 68-,plug-tip 53 and conductors .72 and A11, receiver 5, vthroughth'e switch-hook 73 and again to the transmitter 4. `When the manual subscribers are through talking, ifthe subscriber at sub-'station'jqrOO returns fhis Areceiver 14 to the switch-hook 15,the latter by the weight of the former will be drawn away from the contact-points 16 and 17, thereby .opening the energizing circuit/through the supervisory-relay 39. As soon as theI armature ofthis relay fallstoits normal position in Contact with the contactpoint 84, a circuit is closed through the supervisory-lamp-S, from the grounded terminal of battery B, through the armature 86, the contact-point 84, and the supervisory.- lamp 85, thro-ugh the armature V87, and thence through 'the contact-point 88 to `the non-grounded'terminal ofbattery B. Said lamp will then. Abecome lighted and-the central operatorwill know that the subscriber is through talking. 'The operator 4will then -removethe plug 30 fromthe jaclr31an-d thus break the circuit through the supervisory relay 35 and cut-off-relay 8. The armatures of the latter will then return to their normal positions against the contactpoints 3G and 89, respectively, and the armature 87 of the former leaves the contactpoint 88, thus destroying the circuit through the lamp 85. Again, as soon as the subscriber at sub-station #620 restores his receiver, the energizing-current through the supervisory-relay 81 ceases to flow, and the armature 90 engages the contact-point 91. A circuit is thereby closed through the supervisory-lamp 92 from the grounded terminal of battery B1, through the armature 90, the contact-point 91 and the lamp 92, through the conductor 61 and contact-point 63 to the non-grounded terminal of the battery B1. The supervisory-lamp will then be lighted, and the operator will understand that the sub-station #620 is out of use, and will then remove the plug 54 from the ack "52 and thereby open the circuit through the cut-off-relay 55. Then the armatures l2 and 13 return to their normal. positions against contact-points 93 and 94.

The automatic telephone sub-stations, such as the one represented in Fig. 2, are of the usual type, and are each provided with the usual necessary mechanical and electrical details. Among said details there is, for instance, a receiver in the secondary circuit in series with the secondary winding 101 of the induction-coil 102.k The normal position of said receiver is on the switchook 103, and the latter when Cpermitted to rise opens a normally-close circuit through the ringer 104 at the springs 105 and 106, and at the same time closes the primary-circuit-springs 107 and 108 and the ground-circuit-springs 109 and 110. In series with said ringer-springs and with the ringer apparatus there is a condenser 111. henever the receiver is replaced onV the hook-switch, the latter on its downward stroke forces into connection the so-called release-springs 112, 113 and 114 by means of a short arm-like member 115. In the primary circuit, the transmitter. 116 is in series with the primary winding 117 of the induction-coil 102, and with the two primary-circuit-springs 107 and 108. Said primary circuit terminates at the calling device in two contact-points 118 and 119 which are normally in Contact with the two springs 120 and 121, respectively. The latter constitute the terminals of the line-conductors 122 and 123 that connect the substation #220 with the central exchange. In signaling, the button 124 is the means by which the signaling-spring 125 is shifted from normal engagement with the contact-point 126 into engagement with the contact-point 127.

-The first-selector shown is one Vof a well-known` or suitable type. A well-known type is shown in Patent No. 815,321, granted March 13,1906, to Keith, Erickson & Erickson, and one of this character is represented at C in Figs. 2 and 3. This selector receives the subscribers vertical and rotary line-conductors 123 and 122, respectively. The said conductors terminate in the side-switch-wipers 130 and 131, as shown. Bridged across said side-swtch-wipers are the vertical and rotary line-relays 132 and 133. These relays 3) control the calling mechanism of the first-selector C, through the line-relay-armatures 134 and 135,- and through the line-relay-springs 136, 137 and 138. After' a -firstselector trunks to or makes connection with a connector, said first-selector can only'be re-- stored by means of a back-release-relay 139 and the back-release-relay-springs 140 and 141, as hereinafter described. TWhen an automatic subscriber calls the subscriber #220, the `connection is established over the normal-conductors 142 and 143 that lead from the connector-banks. At the same time, the calling connector-private-wiper, in a manner to be described, connects the private-normal 144 with the ground, and thereby completes an energizing circuit through theso-called bridge-cut-of-relay 145 of the first-selector. Said bridge-cut-of-relay has under its supervision three springs 146, 147 and 1481 Through the first two, the bridging circuit through the line-relays 132 and 133, to which reference has beenmade, is completed. Therefore, whenever the bridge-cut-off-relay is magnetized, the springs 146, 147 and 148 are forced apart by the bridge-cut-off-relay-armature 149, and the said bridging circuit is opened. The object in removing this bridge is to prevent the short-circuiting of voice-currentsV lwhen two subscribers` are talking. The' short-circuiting circuit would be from the line-conductor 123 through the side-switchwiper 130, the vertical-line-relay 132 and the bridge-cut-off-relay-springs 147 and 146,- tlirough the rotary-line-relay 133 and the side-switch-wiper 131l to the line-conductor 122. heneverthe vertical-line-relay 132 is energized, the line-relay-springs 136 and 137 are brought together by the armature 134, and a circuit is closed that energizes the vertical-magnet. 150. Said magnet is composed of two coils 151 and 152, and its office is to operate the-shaft`153 in a vertical or longitudinal direction. The shaft has secured to it a number of circular' ratchetteeth 154 that. serve for various purposes.

Said circularI teeth are used by the verticalpawl155 as a means lfor raising the shaft. Theisaid pawl'is pivotally supported at the end of the vertical arm member 156 formed on the vertical-armature n157, and carries attached to `its rear portion one end of a spring 158, the other end of which latter is attached vto the vertical-arm. Therefore, the said pawl is given a constant ytendency to fall forward against the circular ratchet teeth1541. Said circular teeth, in connection with the locking-,arm 159 on the socalled double-dog 160, actas a locking 4de vice that holds the shaft-whenraised to a new position. Said locking-armfis normally held away from said shaft by a link 161 `known as the Vrelease-link which locks the double-dog in its normal position. The said link is made `of thin spring material and is fastened at one end tothe armature `162 of the release-magnet 163. The free or locking end of this link has stamped out of it a square section, leaving an aperture .161 that receives a 'lug 165 on the double-dog when the switch is in its normal or released condition. Theoperation of these mechanical parts may be described as follows: Each time the vertical-magnet 150 is energized, the vertical-armature 157 is attracted, care rying with it the vertical-arm 156. At each upward stroke the vertical-pawl 155 engages with one of the circular teeth 151- and raises the shaft one step. Atfthe firs-t step the link 161 is lifted from engagement with the lug 165 by anV L-shaped piece 170 attached to the vertical-arm 156. As soon as the doubles dog is released',fthe double-dogfretractingspring 171 draws the locking-arm 159 into engagement with the circular teeth (the double-dog being mounted on pivots 4191), so that when Vthe vertical-pawl returns to its-normal position,the shaft is retained in the new position bysaid locking-arm. It will be understood that the do'uble-dogre tracting-spring 171 isV `properly adjusted to perform the work forwhich itis designed, and has one terminal fastened tothe switchframe and the other to the double-dog. Aft-er the shaft is onceraised, the circular teeth act as a shaft-support whenever said shaft is rotated, butl before any .rotation can take place the private-magnet :172 must be energized. The private-armatur'e '173,

which is supported from the private-,magnet-frame, works in a ,vibratory manner about a horizontal laiiis that .passesv through the supporting points 171` and 175. Said armature is formed with a forwardlyfp'r'ojecting arm 176fhaving two hat surfaces in an Vapproximatelyhorizontalplane. The said arm has a/-short length 177 at its for ward extremity bent downwardly yat righta-ngles' thereto. This arm 17.6- carries'vcertain other mechanical details, viz: a lateral arm 178 designedto controlthe relation ofr the privateespri-ngs 179,180 and 181, fand .a tooth-escapement which includes two flexible springs 182 and 188,- each4 of which/is riveted at one endto thearm 176, one` on the upper side and the other on the lower. Theupper spring is straight and has formed near its forward end two downwardly-extending vtooth projections 181 and 185, while the under lspring" is bent downwardly and then toward the fron-t; This double angle onA the lower escapeinent-spring is so designed that the latter may clear the bent portion177 of the private-arm 176 aoainst which it rests with some degree oi ltension,and vso that there maybe space in front of said bent portion to receive -two othertooth-shaped and upwardly-projecting pieces 186 and 187 formed on the forward end Aof this,,escapementfspring .and which are situated near' the upper teeth and slightlyto the rear thereof. A retractingspring 188, .which has one end attached .to the lprivate-ar'mature and the other to the switch-frame, holds the former normally away from the private-magnet-poleepiece. In conjunction with the escapement above described, there is an escapement-inger 189 whichconstitutes the right extremity of the side-switchearm 190. Said finger is n0rnially retained behind-the' rearmost tooth ,of theV lower escapementspring. The side'- switch-arm has nearthefbase' of said escapenient-finger a forwardly-bent lug '191,l vthe purpose of which is tov limit or control the strokeof the side-.switch-arni when the sideswitch passes from'the first Ito `the second position, at which time it strikes the cam'- piece 192 located on the shaft. The sideswitch-arm may be made to oscillate about pivotal supports 193 and l194; located `near its middle', and said arm carries to .the yleft of its center a rearwardlyproiecting 1ne1n= bfer 195 pivotally connected at its` extremity with a link 196. The' othery end of said link isbifure'ated and engages the lower Yextremity of the downwardly-projecting arm 197 of the double-dog. V ery near the-.flefte-X- tr'emity of the yside-switchear'm there rises a shaft 198 which supports the side-switchwipers 199,200,130 and 131. Thesel wipers are rigidly secured lto the side's-witch-'arrri and as a whole may be-Inade to assume one of three positions. In each of said positions each of these wipers engages one of a series of contact-poii'its r201,` 202v and 203, 2011-, 205 and 206, 207, 208 andy 209, 210, 211 and 212. The,side-switoh-arm with'all itsassociated parts constitutes thje wellknown side-switch arran-gel'nent. which, when i-nthe irst or the switch-frame and by theother to the side-switch-arm 190. When the privatemagnet is energized once, the private-arma.- ture is drawn down momentarily, and then restored. By this operation the escapementfinger 189 passes first from behind the tooth 186 onto the tooth 185, at the downward stroke of the private-armature, and from behind the latter tooth upon the return stroke. As soon` as the escapement-finger clears itself, the retracting-spring 213 draws the side-switch to the second position, and the motion is stopped by the lug 191 striking the cam 192. As soon as the side-switchwiper 199 passes to the second position and, consequently, into contact with 'contactpoint 202, the shaft is rotated. The rotatingforce is provided by the rotary-magnet 214which is composed of two coils 215 and 216.` The rot-ating mechanism consists vof the rotary-armature 217, a circuit-interrupting-arm 218 that works in conjunction with two interrupter-springs 219 and 220, the rotary-armature-finger 2,21 that exercises certain controlling influences over the private-armature, and lastly the rotary-arm 222. This last arm carries pivotally attached to its forward end the so-called rotary-pawl 223. Said pawl has attached to its rear end a small coiled spring 224 the other end of which is fastened to the rotary-arm and which imparts to the rotarypawl a constant forward tendency to engage with -the longitudinal-ratchet-teeth 225. Said teeth are located on the larger diameter of the same member that carries the circular ratchet-teeth and, together with a lockingarm 226 on the double-dog, form the locking means that retains the shaft in any position to which it may be rotated. At each rotary step of the shaft the'locking-arm 226 falls into engagement with one of the longitudinal-teeth. Said locking-arm and longitudinal teeth form the rotary locking means. Vhen the rotary-armature is energized, the rotary-pawl 223 engages with the longitudinal-teeth 225, and the shaft is rotated until the rotary-armature 217 strikes the rotary-magnet-pole-pieces. The energizing circuit of the rotary-magnet passes through the interrupter;springs 219 and 220, and when the rotary-armature is attracted these springs are separated by the interrupterfinger 218. When the energizing circuit is broken, the rotary-armature is drawn to its normal position by the rotary-armatureretracting-spring 227. The ,shaft also carries two wipers 228 and .229 known as the line-Wipers, which are separated from each other and from said shaft by suitable insulating material. Just above `these linewipers, the private-wiper 230 is secured in place and insulated from the shaft. Under the switch parts, and near the line-wipers, theIline-terminal-contacts 231 and the private-terminal-contacts 232 are arranged in banks one above the other. The privatecontact-.terminals are each one electric conducting piece,but the line-contact-terminals are each made of two metallic pieces, one over the other and insulated from each other. When the shaft is raised and rotated, thewipers engage with the contacts of their respective banks, the private-wiper with those of the private-bank, and the linewipers with those of the line-bank. The shaft also carries a coil-spring 233 against the tension of which the shaft is rotated. One end o f the spring is secured to the shaft and the other to the guide or so-called normal-post 234. When the switch is in use, it may be released or restored by the energizing of the release-magnet 163. The releaselink is then thrown` forward, when the release-armature 162is attracted, until it locks with the double-dog-lug 165. Then when the armature is drawn back after the. re-

lease-magnet loses its magnetizing force, the 4 double-dog is drawn away from the shaft 153. `The shaft, if it has been raised and rotated, rests on the shaft-rest 235, and being left to the action of the coil-spring 233 it rotates on the` shaft-rest until the stop-arm 236 p strikes the guide-post 234.

The shaft-rest then enters the channel 237 that traverses the circular teeth, and leaves the shaft to fall to `its normal position by its own weight. There is a so-called normalspring 238 that works between two contactpoints 239 and 240, the position of which spring is controlled by the normal-arm 236. lhenever the shaft is raised, this normalspring leaves the contact-point 239 and engages the contact-point 240. In this way, a guarding potential is thereby` established at the "connector-private-banks," by way of the private-normal-conductor 144, whenever the switch-shaft is raised. It will be understood that the vertical-armature 157 vibrates about 'a horizontal axis that passes through two pivot-points 245 and 246 thatjsupport said armatureon the switch-frame. Similarly, the rotary-armature vibrates in a vertical Vpla-ne about the pivot-points 241 and 242, and the release-armature is supported from the Vpivots 243 and 244. d

The connector may be of the type shown in Patent No. 815,176, granted March 13, 1906, to Keith, Ericksont Erickson. In general the connector is very similar to the first-selector, and many of the mechanical operations of the former are brought about by exactly the same methods and through the same means as in the latter. For instance, the connector is provided with vertical and rotary line-relays'250 and 251 which, when energized, operate the machinery through the mediumof their respective armatures 252 and 253, and a number of springs 254, 255, 256, 257 and 258. The verleas`ed from the release-link- 267=`by the L- shaped piece 268. This release occurs kat the first vertical motion of the vertical-armature. The shaft, afterfbeingraised, is rotated by thel energizingjr of 'the rotary-IJoa-,gnet 269,

throughthe medium of the rotary-armature 270, the rotary-arm 271,1`the rotary-pawl 272v and the longitud'inal-teethI As in' the first,-selecltor,V the rotary-lockiing-arm 247I and the longitudinal-teeth 273 `coi'istitute the locking means for ythe rotary`positioi'isofthe'Y shaft. It vwill he noticed that there is; a difference between Athe* mechanical make-up' of the 'rst-selector-rotary-armature 7 and that ofthe connector, v1The` former has an" interrupterfi'nger i rotary-armature-inger, While the latter has only one arm 271,

namely, the" rotary-arm.' Therefore, the rotation o'f the connector-shaft does not take place automatically, as is the case With the firstselector-shaft,"brit directly as a result or the operation of the callingfdevice of the calling station.y For instance, after the vertical-magnet 260 has raised the shaft a desired number of steps,rl` the private-'magnet 274 is'thenenergized. j The latter carries an armature 275 withl` a` lateral arm 276 having charge of theprivate-spri'n:,rs 277, 278, 279 and 280, and' there being; a tooth-escapemen-t similar to tl'iatdes'cribed in connection with, Lthe first-selector. Said private-armature*carriesy four Aescapement-teeth 281', 282, 283" and@ 284l that Work inv conjunction with theescapement-fnger 285l of" thfe sidesWi'tch-arm V286. This flatter-the,A sidesWitch-arm-is lexactly lthe same as the sides\`v'itcharm of the lfirst-sel'ector and is pro'- vi'ded with Athe cani-lug 287, the arm 288 that holds tlielinkj289wvl`iich iI'ne'sheswith the side-switclr-releasing-arm 290; of the doubledog, and side-switch-Wipers'291, 292,293, 294-v and 295 supported on a shaft249` rigidly fastened to the si-de-sx'vitch-arm 286. The side-switch of the connector is, therefore, the samel as that ofthe"diret-selector?y with the exception that it carriesl five side-switchyWipers instead of four; When the private,- magnet` is energized, the side-switch passes to thefsecondy positiomandjwthe side-switchwipers 291,-y 292;, e931, 294 entreat, in' their 0rder,pass from engagement' with the contactpoi'nts'296`, 297, 29,8, 299' `.and 300 into engagement with the contactoints 301, 302, 303, 304 and305, respective'y.V By the shifting of theside-switch-Wiper 291 from contactljoint 296 tocontact-point301, the local path of the electricalpulsations is change-d from the verticali-magnetto the rotary-magnet, so

that upon the `operationl of the'callin'g,F de-` vice, after the side-switch has shiftedijthe rotary-armature is attractedinste'ad of the vertical-armature, but only once for each electric puls'aftion that traverses the circuit. Each time that therotary-armature is attracted, the rotary-pawl engages with thev longitudinal-teeth 273, just as was described in connection with the first-selector, and the shaft isv rotated step-by-step. rPhe next time that the private-magnet is energized,

after the shaft is-rot'ated, the side-switchl pl'fi'cation,"v Serial No. 258,508, filed May 2, 1905. 'The ,connector, unlike the firstselect'or, is provided' with, only one 'set' of bank-contacts 311-, and with only one' setof Wipers, the line-Wipers 312 andT 313x* "On'the shaft are also yfound the cam 314, ,the nor-y mal-arm 315,' and the coil-spring316. After the connector has been operated so that the Vshaft has been raised, and the Wipers rotated into connection with bank-contactpoints, the switch' may be released bythe energizingv of the release-magnet l31,7. This latter is provided With'an ar-mature 3181that carries an Velongated portion 3191. Vhen this armature is attracted byv the release-magnet, the double-do'g2661 is rotated about the 'pivots 320 and 321, so that the locking-arms 26'5 andA 247 are Withdrawn from the teeth 'on the shaft, and the side-switch driven back at the same timetol its first position and locked' there by the vescapement-finger 285 which engages behind? the tooth 281:y The *double-dog is locked bythe link267 but unlike the first-selector, one end of the said llink secured to the switch-frame and the other endvprovided with the usual aperture 324 that catches the lug 325 of the double-dog andretains the latter, as above described. It iseyi'dentthat when the locking-arms are removed from the shaft the latter will be rotated'vha'ck toward its normal position by the tens-ion of the coil-spring 316i The sha:ft-support326 holds the shaft up, until the normal-arm 315l strikesfthe guideor normal-post 327, at which instant said shaftsup'portthen enters the channel 328,` thus permittingv the shaft to drop to its lowest position, In addition, the L"connector"l is providedwith a difterential-relay 329 hav'- ing two windings 330l and 3,31. 4,aaid relay controls, through its armature 332;, a circuit that passes through tivo springs 33-3and 313,4. This di'liferadial-relayr is So Wound that if the two windings 330 and 3,31 be'conneeted Ifoo its

iro

in multiple, so that the leads 335 and 336 are together', and the leads 337 and 338 are ltogether, a flow of current from one set of said leads to the other will magneti'ze the relay. Or if current passes through one Winding alone, the relay will become magnetized. But should the coils be connected in multiple with the leads 336 and 337 together, and the leads 335 and 338 together, current on passing from one set of said leads toward the other through the coils,- Will not energize said relay, nor Will it be magnetized if current passes from lead 337 to lead 338 When the leads 335 and 336 are connected. There is also a retardation-coil 339, a back-release- `relay-coil 3410 1vith an armature 341, and tWo springs 3-l-2 and 343, and a ringer-relay 3111. This latter, through its armature 34:5, shifts a number of circuits that include the ringerrelay-springs 341-6, 3-17, 342 349, 350, 351, 352, 353'and 354.

For a clear understanding of my invention, it will'be best to follow,` the steps of moving the receiver from the `hook and pressing the button 355 ofthe calling device at the former station six times, and then pressing the button 356 once, the button'355 twice and the button 356 once, and the button 355 ten times andthe button 356 once.

Vhen the receiver-hook rises, after the receiver is removed, the primary-circuitsprings 107 and 108 are pressed into contact with eachother by the lug 357, and the ground-springs 109 and 110 'Hex into engagement when the hook-projection 358 passes out of the way of the latter.V The last two springs, upon coming into contact, complete a connection between the groundpcst 359 and the ground-terminal GG through the following pathz from the ground-terminal G6 through the conductor 375, springs 109 and 110, and the conductors 376 and 377 to the ground-post 359. The calling subscriber then proceeds to press the button 355 six times. Each time that said button is pressed the spring 121 is separated from the contact-point 119 and connected with ground at the ground-post 359. The result is that the vertical-line-relay 132 of the irst-selector C is energized six times by pulsations ot' current Which pass from the grounded terminal G7 of the battery B2 through the ground-terminal G6 to the ground-post 359, the spring 121 and vertical-line-conductor 123, thence through the side-sWitch-Wiper. 130, contact-point 207, conductor 378 and the vertical-line-relay 132, conductor 379, springs 1-1-7 and 143 and the conductors 380, 3.81 and 382 to the nongrounded terminal of battery BV to the grounded terminal G7. Each time that the vertical-line-relay is energized, the armature 134 is attracted and the spring 136 pressed into contact with the ground-spring 137. In this Way, a circuit is closed through the vertical-1nagnet150 from the grounded terminal G7 of the battery B2, through the ground-terminal GS, springs 137 and 136, conductor 383, private-springs 180 and 179 and lconductor 3811, the vertical-magnet 150, conductors 385, 386and 382 to the nongrounded terminal of battery B2 to ground G7. Each time that the vertical magnet is energized, the shaft is raised one step by the vertical-armature 157 and the pavvl 155, and is retained at each advanced step by the locking-arm 159 which is thrown into Working position after the vertical-armature has been attracted the first time. 'By six steps the shaft is raised so that the line-Wipers 228 and 229 are put opposite the irst contact'of the sixth level of the line-bank 231,

and the private-Wiper correspondingly op! positethe irst contact ofthe 4sixth level of the private-bank 232. At the first "step oi the sha'funet only are `the locking-arms released from their normal position, butthe normal-arm 236 is raised awayffrom the normal-spring y233, `Which latterv breal s lavvay from the contact-point 239 and closes in turn "Vuf'ith the grounded contact-point 240. At 'the Ynext operation the callingl subscriber presses the button 356 of the calling device, thereby separating the spring 120 from the contactpoint 118 and pressing said spring against the ground-post 359. A circuit is then closed n'iomentarily through the rotary-line-relay 133 from the ground-terminal GG to the ground-post 359and through spring 120 and rotary-line-conductor 122, thence through the side-sWitch-Wiper 131, contact-point 210, conductor 387 and rotaryline-relay 133, conductor 388, bridge-cutoffrelay-springs 146, 147 and 118, conductors 380', 381 and 382 to the non-grounded terminalfof battery B2 to ground G7. The rotaryline-relay on being magnet-ized energizes the 3rivate-magnet by pressing the line-relayspring-133 onto the ground-spring137. The energizing' circuit comprises the groundterminal Gs and the springs 137 and 138, `conductors 389 and 440, the

private-magnet 172, conductors 391, 386 and 382, and the battery B2 to ground G7. As soon as the Vprivate-nnagnet attracts its armature, the

side-switch passes to the second position and is then stopped `by the cam-lug 191 striking against the cam 192. As soonvas this occurs, the side-sWitch-Wiper 199 closes connection with the sideswitch-contaret-point 202, thereby completing a circuit through the rotary-magnet 214, from ground-terminal G9 to the contact-point 202, through sideswitch-Wiper 199, conductor 392, through ouo of the rotarvfluaguot-oolo 216 oud the interruptor-.Springs 219 aud .220., thouoo through tho .Sooouol lueguot-,ool 215 Aoud cvortho.oohduotoro195, 386 @1191392 to tho hou-grounded terminal of tho huhtolfy BF to ground GT. The looury-orluaturo 217 viS ,ruf luodiutoly uttraotod, aud tho rotary-WW1 22,3, ougos'ug with ltho longitudinal-tooth hoauo to rot-'oto tho Shaft 21,53 Tho cani :192 is, therefore, ,rotated away -iironi the oom-lue' 191., aud `tho .oSoonouoout-ugor 1&9 Lfalls against .the loiver escapement-tooth 187. Immediately after, the locking-arm 226 Ilgolrs the V shaft .in its advanced position, oud @ttor tho ivporo have hoou brought into engagement With the lirst Contact yof the oxthlovol of .their looio-ootvo hahha, bho rinterrupter-finger v 218 then separates the futouruntouonfoso .219 and 2.20, thololoy do- ;oholgiaihs 'tho ,rotary-muguet Tho. rot-arvy armattire`then returns to its normal position, aud tho iorvato-olulaturo, following ,up tho lioturyfarmature-hoger 221, allows the S'do-swtoh to raso fiuto tho ,third nooiftou. TTfho utorruptolsopruss thou llio-u1- Ygage, but not until after the side-switch- .Wplor y199. hoohrohou-,owov :from the ooutaotifioout 20.2 Y

A guordug potential sthon established yat the contact-.point with `which the privateiviperisengafged from the ground-,terminal G1", contact-point 206, fside-switc'h-vviper 200, conductor393, back-release-relay ,139 and conductor 394, private-Wiper 230 to the first Contact of the sixth level' of ,the privatebank 232, to all other 'private-contact- ,points in multiple, this being done as 'soon as the side-syvitcli-iviper 200 passes into Contact ,with ,the grounded contact-.point .206. Also, they calling subscribers lineconductors 123 and 122 are extended to `an idle connect'or `when the side-switch- .Wpers 1.30 and 131 Shitt into contact With ,the `contact-.points 209 and 212, respectively, by Way off the conductors 395 and 39.6, 4line- `Wipers1229y and 228 and over trunk-conductors similar to the trunk-conductors 397 and 398, which former are assumed to be idle. Should said trunk-conductors leading from the first contact-terminal of the sixth level be busy, there Will then be [a guarding {potential at the first contact-,point of thesixth level of the private-bank, ,establiSlleCl there by some occupying-switch, and over a circuit similar Ito the one already described in foonnection Withfthe side-svvitoh-Wiper 200. ,when

the latter passed into connection vvith `the vcontact-point v206..A Assuming, also, that the first and the next succeedingY eight trunks or Ltrunk-lines of the ,sixth .level lare busy, lthere will fbe a guarding potential not only at the first,priyate-contactofthe sixth level, butalsoat thesecondnthird,etc., eighth and ninth. The yviperslbeingpPOSite .th'e first oolituot of. the sixth.' larsl, if the .calling lsub- .lao-.1.111

sorhor how .grounds ,tho rotauysluo-oouoluof to); .122 :hy nrooous tho button 3.56,-thoruvat-o-Ihosuotui-,1lho ouoruod oolootore, oud tho A4o.idosutoh. will ho flovvh luto the soc'- ohol ,rootiou Tho ,S-dofoWtoh-.Wipof 199, unou kkoloous Awith `ooutuot-rouot 20,2., ohohco ouoiezos tho rotary-mocha, and thou. 'tho .hotaryfpoul 223 rotatoo tho Shaft-Wipersiuto ousasorueub with .the first 'contoots of tho sixth level gf Vtheir respective banks, but

.thooo wiper-S will hot ooop thoro- A orout ofoloood throushtho privato-magnet, os Sooo4 as the private-Wiper 230 strikes the first buoy ooutuotfpout, ou followsr from `tho grounded terminal' G7 of ,the battery B2, through the SWto-h ooouPy-og tho first .truuk ofthe sixth level and circuit ynot shown, to ,the first contact-point ofthe sixth llevel of .tho `privato-bah1 232, through :tho privato- `rviper 230, conductor 3941, the back-.releaserelay 139, thence through the side-switch- .yviper 200, contact-point 205 and conductors 397 and 40, tho privato-magnet .172, ooniduotoro A3,91, 386 'and 38.2 to tho-uougfouudod Yterminal of .battery B2 .to `ground G7. VThe side-.switch is, therefore, held inthe second position by vthe yprivate-armature through fthe. Imedium ot the toothescapement. As soon as the -interrupter-lingcr separates the 'interrupter-springs, they rotary-magnet .is cle-energized, and the rotary-armature re- -turnsto its normal position; but the privatearmature does not follow, the private- .magnet being still magnetized. As soon as the interrupter-springs re-engage, the r0.- vtary-magnet is once more energized, and the .side-sivitchiviper 199 being still retained on contact-point 202, the shaft is rotated one more step, Garrying'the private-Wiper onto .the second contact"of-the sixth level, Which Contact-point `also has guarding potential. As soonasthe interruptor-springs 219 and 2.20am again separated `by the vinterruptor- .fingen the rotary-armature once ,more returns toits vIfiormal position; vbut still the private-armature does not follow. In this Way, the shaft is rotated step-by-step as long as the private-Wiper continues Ito encounter v`privatei-contact-,points with guarding potential. After the- Wipers are rotated into connection with the ninth bank-contacts .of `the sixth level, the rotary-magnet is once -more energized, and thusthe Wipers are r0- tated onto thetenth contact. 'The interruptor-springs are again separated and the rotary-armature begins once more to return vto itsnoigmalposition. As soon as the private-.Wiper leavesfthe ninth contact of' the vSixth Vlevel and .passes onto the tenth contact, the -energizing circuit through ,the private-k magnet ,is ,broken, and the private-armature falls against the rotary-armature-.linger 221 Which fis still depressed. As' thel rotaryarmature returns the privatearmature 'also returns to vnormal position, and the sideswitch passes to the third notch before the interrupter-springs again engage. At the end of this automatic rotation, a guarding potential is established at the tenth contact of the sixth level, and the subscribers line is extended over the line-wipers 229 and 228, through the trunk-conductors 397 and 398 to an idle connector. This connection is clearly shown in Fig. 2. lvVhen the called subscriber neXt presses the button 355 twice,

the vertical-line-relay 250 of the connector,

D is energized twice by a current passing from the ground-terminal G to the groundpost 359 and over the vertical-line-conductor 123, side-switch-wiper 130, contact-point 209, conductor 395 to the vertical-line-wiper 229 of the first-selector, thence through the vertical-trunl-oonductor 397, the connectorvertical-line-relay 250, the winding 331 of the differential-relay 329, thence through conductors 338, 399 and 400 to the nongrounded terminal of battery B2to ground G7. The armature 252 of the connectorvertical-line-relay 250 then presses the spring 255 against ground-spring 256 twice, thus energizing the vertical-magnet 260 twice through a circuit from ground-terminal G11 through springs 256 and 255, conductor 401, private-springs 278, 277, conductor 402, vertical-magnet 260 and conductor 403, through contact-point 296, thence through the side-switch-wiper 291, the conductors 404, 405 and 400 to the nongrounded terminal of battery B2 and to ground G7. `Each time the vertical-armature is attracted, the shaft 259 is raised one step, and the line-wipers 312 and 313 are, therefore, raised to a level with the second row of the line-bank 311, and opposite the first contact thereof. At the sub-station #220, the button 356 is next pressed, only once, and the connector-rotary-line-relay is energized through a circuit as follows: from ground-post 359, and over the rotary-trunkconductor 122 to the first-selector-sideswitch-wiper 131, through the contact-point 212, conductor 396 to the rotary-line-wiper 228, and thence over the rotary-trunk-conductor 398, through the rotary-line-relay 251 of the connector, conductor 335, winding 330 of the differential-coil 239, the conductors 337 and 406, ringer-relay-springs 347 and 348, conductors 407, 405 and 400 to the non-grounded terminal of battery B2 and to ground G7. When the rotary-line-relay 251 is energized its armature 253 presses the line-relay-spring 257 against ground-spring 256, thereby closing a circuit through the private-magnet 274, from ground-terminal G1l through the springs 256 and 257, conductor 408, private-magnet 274, conductors 409, 410 and 406, ringer-relay-springs. 347 and 348, conductors 407, 405 and 400'to the nou-grounded terminal'of battery B2 and to ground GT. The private-magnet, when .en-

ergized once, attracts its armature once,

causing the escapement-inger 285 to disentact-points 301,302, 303, 304 and 305, re?

spectively. The next thing that the calling subscriber does is to press the button 355 ten times, this operation corresponding'to the third digit of the number that is being called. The vertical-line-conductor 123 is thus grounded ten times, and the vertical- Vline-relay 250 is energized ten times through the same circuit as before. Each time the springs 255 and 256 are brought together the rotary-magnet 269, instead of the verticallmagnet, becomes energized through the following circuit: from ground-terminal G11 through the springs 256 and 255 andconductor 401, private-springs g 278 and 277, conductor 411, the'rotary-magnet 269 and conductor 412, thence through contact-point Y 301 and the side-switch-wiper 291, the vconductors 404, 405 and 400 to the non-grounded terminal of battery B2 and to ground G7. Each time the rotary-magnet is energized the rotary-armature 270 is attracted vand the rotary-pawl 272 engages with the longitudinal-teeth 273 androtates the shaft one step. At the end ofthe tenth step the line'- wipers 312 and 313 will be engaged with the tenth contact of' the vsecond level of the connector-bank 311 and, therefore, with the normal-conductors 421 and 422 that lead to the called subscribers station. Then, as soonk as thev calling subscriber presses the button 356, the rotary-trrink-conductor` is grounded once, andthe rotary-line-relayl of n the connector is once more energized through the same circuit as before. l The private-magnet is then energized again by the closing of springs 256 and 257. Then the private-armature is operated, the sideswitch passes to the third position by reason of the escapement-finger 285 disengaging first from the tooth 284 and then from the tooth 283. As soon as the side-switchwipers 291 and 293 close with the contactpoints 306 and 308, respectively, an energizing circuit is completed through the ringer-relay 344, from ground-terminal G12 through contact-point 308, side-switch-wiper 293, conductors 413 yand 414, the ringerrelay 344 and conductor 415, differentialsprings 333 and 334, conductor 416, contact- 1 fjiinigmaturep345 then-,forces the ringer-relaythe springs 1348, '.351 and 354 .into --engzng ement With the springs 346', 5, .349 end' .352'. When .the springs 347 346, .close contact, sun'icient energiznIlling., ou rrent'y is .sent over theline through ,tfhegfcellifngsub-station forthe purpose of energizing Athe.talling-eireuit et such place.

and

'The" fpth of V.this electric battery-Current Al.lineconductor 123, .thence `through the side- Jswitch-Wiper '130 of the first-selector C,

cont'act-.points209,conductor 395,- the Verti- 39, callinewiper 229,..end .the Vertical-trunk- `conductor 397, verticel-.line-reley 250, condueto-r 336,; Winding .331 of `.the differential- Arelay grounded terniinl of battery .B2 and t0, fl'igroundG VA ifterrtheside-Switch .passes to 'the' third position, land the,` side-switch- :Wipers- 293 y@and 291, respectively, come in .l contact-with .they contact-points' 303 and 30G,

'A endV ffterthe ringing-relayjis energizechend ehvtheisprings() `and. 353, respectively, yare Y pressedinto contact. with `the springs 349 en d 2,zthe calling.v line is extended tothe ,normal-conductors 421 end422 -through the fwcondensers 425 ,and 426 and conductorsf4244 Ilfandfy 427 y tothe vvline-Wipers 312 and 313, by wey oft-the side-sWitch-Wipers 294 and'295 j and conductors 423 and428.` kAlema circuit isl .completed ,through Athe cut-ot-reley of f y the.manualsubscrihei ,Seid circuit rmay he l 'traced from ground-terminal G4 through..the

'fout-off-reley 55, the .vertical-trunk-conduc-- torf421:andthe vertica-l-line-Wiper 312 of' the connector D, conductor423, contactffpoint v309, the side-sWtch-wiper 294 end.

thence .through the .ringer-reley-springs 350 Yand .349, .conductor .424, `the retardation-coil ,339 I.andcoi'iductors 399 and 400 to thenon- .-f

y springs 333 and 334'are seperated. 1t Will f beunderstood .that these two springsl are ineluded inv the energizing circuit of the ringer-relay.

.grounded terminal 4o'l batteryy B2 4and to vground G7. .Seid out-oit relay is thus ener- GOfgzed, and the c ut-o-relay-armatures 12 end: 13 are attracted,.fthereby completing 2ry yconnection het-Ween the calling su'hscrihei"s line and therdesired subserbesstation over,

ltheiollowving c-rcut from the transmitter 5 116 through the primary .i'inding 117 ot' the ,springs .347, 350 and 353, respectively, .away

329,the conductor 400 -to they non- I ground-terminal end 110, the contact-point 127 end the siginduction-coil' 102, over conductors 418 and y417, `the rotaryline conductor 122 andthe first-selector-side-switch-Wiper 131, the contact-point 212 and conductor 396, thence. through the rotary-line-Wiper `223 to 'the` trunk-conductor 393, through the condenser 426 .of connector D, conductor 4217, ringerrelay-springs 352 211161353, the side-switch- Wiper 295'end the contact-point 310, thence vthrough .conductor 428, the rotery-lin'e-W yWiperv 313, the' rotary-trunk-conductor l422, contactpoint,67,.the armature 13 of cut-offrele-31,55 and conductor 11, through 4the condenser 3, the switch-hook 73 and the ringer l2, conductor'lO, armature 12, contact-point 6.6,-,the verticel-normel-conductor 421, and

Vthe, vertical-Wiper 312 of connector D,

c0nductor423, contact-.point 309, andthe side-sWitch-Wiper 294, through the ringerrelay-springs 350 and 349, the conductor 42.4, and .the condenser 425, the verticaltrunk-condnetor 3.97 the verticel-line-Wiper i229 of the inst-selector G, conductorv 395,

4contact-point 209, side-sWitch-Wiper l130, conductors 123, 420 and 419, tlie` priniery' circu'it-sp-rings 103 and 107, spring. 1125 contact-point 126, and again to the transmitter 116. Having completed 'his connection, the 'calling subscriber next kpresses the ysignehng or ringing-button 124. When said 1 button is pressed,. the spring 125 is seperated frointhe `contact-point 126, thereby separating thevertical-line-conductor, of which the spring-125- is e terminal, ronrthe rotaryfl'i'ne-conductor,of which the Contact 126 is n terniinel,.and grounding. said vertical-linec'onductor "against the contact-point 127. The .effector grounding the Vertical-.conductor `itthis time is to energize the Verticlline-re'lay 2.50 of the connector D, and 1 `elso. th e d ierentiel-relay 329, hyenergizing theCQijl V331. This circuitY entends from the l through vsprings 109 nailing-spring .125, the .primary-circuitsprmgs 1 07 end 108, conductors 419 :1nd 420,

fthe contactpoint 119 and the spring 121,

zind400to the non-grounded terminal of 'battery B2 and vto ground G7. The energizingfof theI Vertical-line-reley .et this time [has no utility; hut as Soon as the diiferen- `,tial-relay 329 is energize-d the armature 332 1s, attracted and, the ,dirl'erential-reley- Therefore, when the suhscriher presses .the signaling-button and en- .ergizes the y differential-relay, the ringerreleyis cle-energized and the ringer-relaysprings resume .their normal positions. The

` 1 are one andthe same machine.

,relay-springs 351 and 354 ringer-relay-springs 350 and 353, after separating from the springs 349 and 352, reengage With the springs 351 and 354, respectively. The ringing-current then passes from the ringer-generator R to ground G5 and to the grounded terminal G3 ot the battery B1 of the manual exchange, through said battery and conductor 7 5, retardationcoil 74, conductor 429,V ringer-relay-springs 351 and 350, through the side-switch-iviper 294, contact-point 309, conductor 423, the vertical-1ine-Wiper 312 and the verticaltrunk-conductor 421, contact-point 63 and armature 12 of the manual subscribers cutott-relay 55, through the conductor 10, ringer 2 and the switch-hook 73, through condenser 3 and conductor 1.1, armature 13, contact-point 67, the rotary-normal-conductor and the rotary-Wiper 313, conductor 423, contact-point 310, through the sidesWitch-vviperi295, the ringer-relay-springs and 354 and conductor 430 to ringergenerator R. It will be understood that the ringer-generators represented in Figs. 4 and Also, it Will be seen that when the ringer-relay is le-energized and the spring 350 separates from the spring 349, the circuit that was described. as the ener'iZin r circuit ot the cutott-relay 55 is then opened. The cut-offrelay is therefore cle-energized, but only for a very short period of time, for as soon as the terminals of the ringer-generator R are ln'ought across the normai-conductors 421 and 422-When the ringer-relay-springs 350 and 353, respectively, close with the ringeranother circuit is established through said cut-ot-relay. The said circuit extends from the nongrounded terminal of battery B1 and conductor 75, through the retardation-coil 74, conductor 429, ringer-relay-springs 351 and 350, sideswitch-,Wiper 294, contact-point. 309, conductor 423, vertical-line-Wiper 312, vertical-normal-conductor 421, cut-oit-relay 55 to ground G4 and back to the grounded terminal G3 of the battery B1. In this Way, the cut-otlrelay is maintained in an energized condition even `While the ringing-current is being passed to the line of the desired subscriber. As soon as the calling subscriber releases the signaling-button 124, the vertical-line-relay of the connector, and the diiierential-relay, again become deenergized, and the differential-relay-springs 333 and 334 again close contact With each other, thus restoring the energizing circuit oit the ringer-relay. As soon as the receiver' 5 is removed 'from the switch hool 73 ot the sub-station :#620, a circuit is closed through the transmitter 4 of said Sub-station, which provides said transmitter withenergizing-current for talking purposes. Said energizing-circuit extends 4from the non-grounded terminal of the battery B2 through conductors 400 and 399, the retardation-coil 339, conductor 424 and the ringer-rela-y-springs 349 and 350, side-sWitch-Wiper 294, contact-point 309 and conductor 423, the vertical-line-Wiper 312, normal-conductor 421, contact-point 66, armature 12, conductor 10, transmitter 4, switch-hoch 73, through the retardationcoil 6, conductor 11, armature 13`andcontact-point G7, 4the rotary-normal-conductor 422 and the rotary-Wiper 313, conductor 428, the contact-point 310, conductor 431, through the hack-release-relay 340, conductors 432 and 413, side-sWitch-Wiper293, contact-point 303 and to ground G12. The subscribers are now in position to communicate With each other. 1t is evident that the receivers of the two sub-stations in communication are not connected metallically, but inductively, as the receiver ot sub-station #-620 is bridged across the retardation-coil G through the condenser 3. Now, When the subscriber at sub-station .7E/:620 talks into the transmitter 4, variations are producedv in the resistance o't' the circuit, and in the intensity ot the electric current that passes through said transmitter. These variations are transmitted through the conde-users 425 and 426 to the circuity of the calling sub- ,scriber that contains the primary Winding 117 ot the induction-coil 102. Corresponding variations are in turn induced into the secondary Winding 101 ot said inductioncoil and the receiver 100 in series. Therefore, when the subscriber at sub-station #620 talks into his transmitter, the subscriber at the calling sub-station can hear what is said. In turn, when the subscriber at sub-station .#220 talks into his transmitter11f, variations are produced in the intensity ot the current that passes through said transmitter, and these variations pass over the same circuit, through the condensers 425 and 426, and reach the receiverv oi sub-station #6.20. currents,` it Will be from one sub-station to another over the circuit that connects the ltivo sub-stations, and i Which has been pointed out. When the tivo subscribers, are through talking they restore their receivers to their places. It the switch-hook at sub-station These talking- :t-G is drawn down iirst, the energizing circuit through the transmitter 4 is then broken as soon as the hook leaves the two contact-points 75 and 7 6, and the ringer 2 with the condenser 3 are restored in series across the line-conductors 10 and 11. NOW, When the receiver 100 at sub-station #220 starts the switch-hook 103 on itsdoivnvv'ard motiointhe three release-springs 112, 113 and 114 are tiered together and into contact. The rot-ary and vertical line-conductors 122 and'123 are thereby simultaneously 'grounded. The grounding of the rotary-line-conunderstood, pass ductor 122-a't rst Iaccomplishes nothing,

' since -it is Vat `this time 4grounded not only short-circuited through the ground. Said :short-circuit may be traced from the ground- .519 terminal GG attrib-station #220, through the ground-springs 109 and 110, conductory 376, release-springs 114 and 113,conductors at the release-.spring 114, but also at the ringer-relay-spring 346. Therefore, no eur- .Yrent passes through the rotary-line-relay 251, nor through the winding 330 of the differential-relay 329, since these two coils are 433, 417, spring 120, thence over the rotaryline-conductor 122 to the "irst-selector-sideswitch-wiper 131, contact-point 212, conductor 396, through the rotary-line-wiper 228, the trunk-conductor 398, thence through the rotar 7-line-'relay 251` the conductor-335,

and the winding 330 yof the differential-relay 229, over the .conductors 337 and 406, and

soon-as lthe said 4differential-relay becomes energized, the armature 332is attracted, andv the differential-relay-springs 333 and 334 rare sepa-rated. The energizing circuit through the ringer-.relay 344 is .thereby i broken, and the ringer-relay-springs 347 and 346 return to their normal positions. At the instant that the ringer-spring 347 comes into contact with the adjacent spring 348, the rotary-line-.relay 251 becomes energized, as Well as Athe winding 330 ofthe differentialrelay 329. Under these conditions, both of the windings vof said differential-relay are energized, but the current passing through them-does so in such relative directions that they simply augment each other. Therefore, the differential-relay remains energized, even after .the line-relay-springs 254 and 258 come into contact, and remain sol as long as both the rotary andntheyertical linerelays 251 and 2,50 are keptenergized. As .soon vas said springs close contact, an energizing circuit is completed through the connector-release-magnet 317, in series with the back-release-relay 139 of the first-selector C. The current passes from the grounded terminal G7 ofthe battery B2' to .the ground-terminal G10 and to the side- 4switch.-contact-point 206, through the sideswitch-wiper 200, thence through conductor 393,. back-release-relay 139 to the private- .wiper V230, v thence .over .the .trunk-release- .conductor 434, through the line-relay- .springs 254 and -258over the conductors 435. Y and 436, .through the release-magnet 317,.

conductors 437 410 land 406, Ythrough the ringer-relay-springs- 347 .and 348 and the .conductors 407, 405 and 400v to `the nongrounded terminal of thebattery B2' .and to ground G7. As soon as the releasemagnet 317 of the connector D .becomes energized, the release-armature 318 moves the doubledog 266 away from the shaft yand locks it with the release-link 267. The connectorshaft is then restored to its normal position, as well as the lside-switch. A.t the same time that the "connector-release-magnet 317 is energized, the haclr-i'elease-relay 139 of the first-selector C is energized also, as was stated, and the hack-release-relay-arma.- ture 438, upon being attracted, presses the back-release-relay-springs 140 and 141 into contact with each other, At once the firstselector-release-magnet" 163 becomes energized byv the ycurrent that passes from the grounded terminal G7 `ot the battery B2 to the ground-terminal G1", through the back-release-relay-springs 141 and 140 and over the conductors 439 and 340e, through the release-y magnet 163 and over the conductors 385, 386 and 382 to the nongrounded terminal of the battery B2' and to ground G", When said release-magnet 163 attracts its armature 162, the release-link 161 is thrust forward, and the double-dog-lug 165 is caught in the aperture 164, remaining so as long as said release-magnet remains energized. When the switch-hook at ysub-station #220 has descended far enough, Vthe member 115 of said hoot: clears the .release-spring 112, and the vgrounding circuit to the rotary and Vertical line-.conductors 122 and 123 is interrupted as soon yas the release springs, by reason of their own tension, regain their normal positions. The rotary and ifertical line-relays 251 and 250 of the connector D immediately become de-energized, and their armatures 253 and 252, by returnto their normal positions, destroy the continuity of the energizing-circuit ,through the` connector-release-magnet 317 and through the yfirst-selector-baek-release-relay 139. The 4armature 318 of the connector-release-niagnet then returns to its selector. It is evident that should the subscriber at sub-station #220 restore his receiver first, the releasing of the Erst-selector C and the connector D would then take place in the manner described. But as soon as theV Aconnector is released, the

shaft in returning to its normal position, causing. the linewipers 312 and 313 to disyengage from the normal-conductors 421 and l422, would destroy -the energizing-circuit through -the cut-of'f-relay 55, and through y the transmitter 4, thereby cle-energizingv the said relay and transmitter. The armatures 12and 13 then return to their normal lpoyground G".

sitions, resting against the contact-points 93 and 94, respectively.- It has been shown, therefore, how the calling subscriber obtains his number when the Way is clear; but had the number 620 been busy, the connector7 would have been released when the privatemagnet 274 was energized after the sidesWitch Was in the second position. Should the manual subscriber #300 be connected with the manual subscriber #620, it has been pointed out that the supervisory-relays and 81 and the cut-otf-relay 55 are energized, and, therefore, that the normalconductoi 422 is connected with ground G3 through the supervisory-relay `81, conductors 80, 62 and 79, plug-tip 53 and a conductor 72. NOW, it the rotary-line-conductor is grounded by a calling subscriber' pressing the button 356 while the connector-sideswitch7 is in the second position, the connector-private-magnet 274 is then energized, and the springs 279 and 280 are closed together. As soon as they come into con-- tact, the back-release-relay 340 of the connestor becomes energizedk by a current passing from the grounded rotary-normal-conductor 422 through the rotary-Wiper 313, conductor 428, contact-point 310, conductor 431, back-release-relay 340, conductor 432, side-svvitch-Wiper 293, contact-point 303, conductor 441, private-springs 279 and 280, conductors 442 and 436, release-magnet 317, ringer-relay springs 347 and 348 to the nongrounded terminal of battery B2 and to It is evident that the enerfizing-circuit through the back-release-relay 3410 passes through the release-magnet 317;

but the magnetic force developed at theV lat-` ter is not sutlicient to operate the releasearmature 318. This is due to the fact that the number of turns ot they Wire Wound on the electro-magneti'340 is larger than that ot thesame Wire of the electro-magnet 317; also, to the tension of the spring against which the release-armature operates. The resistance of the black-release-relay is approximately 500 ohms, While theresistance ot the release-magnet is only about 60 ohms. However, as soon as the back-release-relayarmature forces the springs 342 and 343 into engage-ment, the back-release-relay-coil is short-circuited, and the release-magnet then receives enough current to attract the release-armature. The energizing-circuit f through said release-magnet is now from ground G1 through the back-release-relaj,7

springs 342 and 343,conductors 443 and 441,-

private-springs 279 and 280, conductors 442 and 436, through the release-magnet 317, conductors 437, 410 and 406, ringer-relaysprings 347 and 348, conductors 407, 405 and 400 to the non-grounded terminal of battery B2 and to ground G7. The short-circuiting or shunting of the back-release-relay takes place through the ground-terminal G15 and the back-release-relay-springs 342 and 343,

conductor 443, contact-point 303,' theside- Y switch-Wiper 293 and the conductors 413 and 432, through the bacl-release-relay 340, conductor 431, contact-point 310, conductor 428 and `rotary-Wiper 313 tothe grounded normal-conductor 422. As soon as the release-magnet becomes energized, the connector-shait returns to its normal position, and the side-switch is moved to the first position. The calling subscriber, thinking that he has established connection, will press his signaling-button 124, thereby grounding the vertical-line-conductor, which at this stage, since the connector is released, has the effeet ot only raisingthe shaft olf-normalL- that is, from its normal position. vAs soon as this occurs, thenormal-spring 444 engages with the contact-point 445, and a busy signaling-current, of a buzzing nature, is thrown across thereceiver. `The apparatus for producing the busy-signal consists of a circuit-interrupter 446 Fig.' 2) in series with the primary Winding 447 of an induction coil 448 between -the non-grounded terminal of the battery B2 and the ground-terminal G16. The induction-coil 448 has a secondary Winding 449 through Which an alternating' current is duced by the interruptions in the'current that `passes through the primary'winding 447. It is across the coil 449 that the receiver 100 or any other receiver that-receives the busy-signal isbridged. The busy-circuit extends through the secondary Winding 449 ol the induction-coil 448, and passes through conductor 450, the side-svvitch-Wiper 292,

contact-point 297, conductor 451, the normalf vspring 444 and the` contact-point 445, conductors 452 and 427, condenser 426, conductor 398, Wiper 228, contact-point 212 and the side-sWitch-Wiper 131,4 conductors 122, 417- and 418, primarywinding 117 of inductioncoil 102, the transmitter 116, contact-point 126, spring 125, and springs 107 and 108 over conductors 419 and 420, conductor 123, through the side-sWitch-Wiper 130, contactpoint 209, the conductor 395 and the vertical- Wiper 229, conductor 397, the vertical-linerelay 250, conductor 336 and` Winding 331 of differential-coil 329, conductors 338, 399 and 400, and back to secondary Winding 449 algain. The calling subscriber Will then recognize that the number he Wishes is busy,- and Will restore his receiver, thereby grounding both line-conductors 122 and 123 simultaneously. The groundingtof theseconductors, ithas been pointed out, results in the simultaneous yenergizing of the i line-relays 250 and 251 of the connector and, theretorefot the release-magnet of the connector and'ol:l the back-release-relav of the first-selector inseries. It has also been pointed out that Whenever this occurs, the release mechanismv is energized, and it is thenevidentthatf the svvitches will be released;j In the connector however,y the sha1-'ft l will ,not rotate" at all-When the release mechanism is operated, but will only drop straight down, 'since the shaft had only been raisedby the pressing of the buttonv124, and not rotated. couldbe Abusy also by having been called by Aanother automatic subscriber. In that case,

switch-Wiper 293-', conductors 413 and 432,' back-release-:relayI 340, lconductor 431, con-'v tact-point' 3:10,' conductor v423, rotary-,line- Wi'per "313 toV the v'rotary-normal-conductor '422. Thenside-switch of the calling connectfor being in the second position Whenv therotaryelineconductor is grounded, the

backsrelease-"relay Y340 isI energized through a circuit beginningi'rom a ground-termina'lY `Vsiinilar to` ground-'terminal;G12 of the occupyingconnector, and a back-release-relay to i' -`the rotary-normallconductor 422, as

traced above," thence through the rotary-line-4 Wiper v313, Aconductorsy423 and 431, back- \-"releaSe-relay` 340,co'nductors 432 and 413,-

side-switcli wiper 293, contact-point 1 303,

conductor 4441, private-springs 279 and 230,l

conductors 442 andl 436,'release-magnet- 317,

conductors 437, 410 `and '406,ringer-relay# springs 347 andf'348, conductors 407, 405 and 2 400 ito'ithe nonfgrounded terminal'of the battery B2 and tog-round G1; land in this Way the release-magnet 317 becomes V energized, and .the connector 7 isreleased'.y The call- Y ing subscriber, upon: pressingl the Isignalingbuttoii, 'gets the nbusy-signal and then" restores "the switchesfby hang-i-ng-up 'his receiver; 1 It, While lthe automatic and manual subscribers :1E/:220,A and #620 are connected,-

a second; manual 'sub scriber1:,.1,l300, for in'- stance ,'(Figzr V1) calls for l:/;;:=620, the manual operator willtv test the line #620 bystrilring the jaclr-sleeve 57`With thevcallin'g cord-tip 53, and WillI get abusy cliclr throughthe `re-vk cei'\'fer,=\vhich will indicate that -subscriber #620 4is busy. When th'e tip 53 strikes: the

sleeve 57 ,k a circuit is1closed through the test.

relay`453'from ground G3 through vthe teste relay 453,t conductor 454, armature 62,' conductor 7 9, lcontact-point 77, spring '68,"tip 53,1sle'eve 57, :conductor 56, vertical-normalconductor `421, `vertical-Wiper -31'2 of con-4 nector D, conductor 423, contact-point 309,'

si-de-sw'vi'tc-h 294, ringer-relay-springs 350" and `349-to conductor 424, retardation-coil339,

conductors 399 and 400 tothe non-'grounded terminal off the battery B2 andto ground G7. hen'the test-relay is energized, it'sa'rina'- ture 455 Aiswattracted and drawn against the' cdntact-point'456. -This Will' close a circuit through the Winding 457 of the induction-- The manual line in question,

455, `contact-point 456, ivinding 457 of induction-.coil-458, conductors 459 and 7 5l to theI non-grounded terminal of the battery B1 andl to `ground G3. As the operator for a vmoment simply touches the tip 53 to the coil 458, vfrom ground G3 through armature jack-sleeve 57i,- the test-relay 453 will be'` energized just for a moment, thereby causing fonly a momentary flow of current through theyvinding 'of the induction-coil 458. Amagnetic ieldis created about said Windingthat'will induce a current in the coil 460. This latter coil is in series with the receiver 47. The circuit `of the induced current isvfrom the Winding 4600i ythe induction-.coil 458, throughthe -receiver 47, spring 43, conductors .43 and 7, tip-spring 42 oi answering-jack 31, conductor 41, armature- 20, conductor 21,'switch-hook 15, transmitter 23, vconductor 24, armature 25, conductor 32,

jack-sleeve 33, conductors 34 and 49, spring 44, contactpoint 46, condenser 461, and back again tothe coil 460. The -tvvov springs 43 and 44 arepressed against-,the contact-points 45 and 46, respectively, While ythe operator makes .the-busy-test. The'operator will theninform the calling subscriber that the numberv is busy.` Y. y e l Y Therefore, from the foregoing, i-t is clear that` if two manual` exchange subscribers are connected, an automatic line cannot connect WithIe-ither 'of said subscribers; nor if anz automatic and a manual line are connected can a second automatic line" connect with' said-manualline. 1n the latter case,v alsoy-shouid a second manual exchange sub-l scriber desirey connection with said engaged manual line, the operator in making a test willget vthejbusy-cliclr. No reference has been'made tor methods whereby automatic subscribers connect' Withy automatic vsubscribers, orl whereby fmanual subscribers connect With `automatic subscribers, since this-is not `necessaryv to a full understandingvofl my invention. Amy. one' ofv a number of methods vmay be used for such purposes, according to the' requirements ofl different cases. My present'invention comprises, it will be seen, an improved connec tor"and` means Vfor connecting the jacks of themanual lines withlthe banks of said improved fconnectors. `It is evident that aV desirable ymethodA of numberingthe lines ot'l the tWo systems would .beL to 'number the V'automatic lines from K 100 through the fifth alreadybeen suggested by the numbering'of f the: stations, it'nis clear thatthe-iirst iive levels' of the firstselector-banks lead in the direction of I the' automaticsubscribers and thatfthe V'sixthto tenth levels, inclu#V sive, lead to .my improved connectors -and thencev to -the manualcsubscribers.' The above principle, as applied to one thousand said side-switch, when it springs into the third posit-ion, causes the ringer-relay to become energized, that the latter by so doing closes a circuit that conveys the current for energizing the transmitter of the calling automatic subscriber, and that the current for the talking-circuit of the calling' line is under the control of the ringer-relay in the connector, Said energizing-chouit contains the vertical and rotary line-relays, as explained, and also the windings of the differential-relay on the connector in use. The former relays, therefore, become energized and remain so during a connection, but the differential-relay remains inactive, since'the direction of the current through the windings of the latter, at such time, produce in it magnetizing forces that neutralize each other'. The vertical-line-relay and one winding of the `differential-coil are locatedbetweeno-ne side of the talking-circuit and the common battery,` and the rotary-line-relay and the second winding of the differential-coil between the other side of said talking-circuit and said common battery. The coils, by their inherent resistance, regulate the amount of currentthat is maintained in the calling line when it is in use, and they also furnish impedance to prevent the flow of voice-currents through the battery B2. On the other hand, the circuit through which energizing-current reachesV the transmitter of the called manual exchange subscriber, when an automatic linel is connected with the former, comprises two normally open contact-points. Gne of said points is closed whenthe side-switch Vpasses to the third position, after the connector has made connection with the called line.`

The other point is closed` by the switchhook at the called station when the receiver is removed from its hook and the latter is permitted to rise. 1n said energizing-circuit there are `included two coils, the connector-back-release-relay andthe connector-retardation-coil. These coils are used between the battery-terininals and the talking-circuit and serve to regulate the amount of current that passes through the trans-` mitter of the called station. The connector-baclr-release-relay is located between one side of the talking-circuit and the battery, and the retardation-coil is located between the other side of thetallring-circuit and the battery B2. These coils also, by reason of their impedance, serve to prevent the voice-currents from short-circuiting through the battery that furnishes talkingcurrent. Therefore, talking-current, when an automatic exchange line is connected with a manual exchange line, is furnished to the several stations through independent circuits, and from special points in the connector- The leads from the ringer-generator are normally connected with the lower two sideswitch-wipers, but become disconnected from said wipers as soon as the ringer-relay becomes energized. An important point in connection with my improved connector is that. the release-magnet, the privatemagnet, the rotary-line-relay, and the winding of the differential-relay that is in series with the latter are allfby a commonlead, connected with one of the ringer-relay springs which is normally in contact with a second relay-spring` that constitutes the non-grounded terminal `of the battery. liilhen the said ringer-relay becomes energized, the coils above named are disconnected from the main battery at a point between the two springs just described. Therefore,

for the reason that the release-magnet among `said magnets is retained disconnected `from the non-grounded pole of the battery while the ringer-relay is energized, the connector7 is not released when the talking-current to the transmitter of the calling substation energizes the rotary and Vertical line-relays of said connector.. lVhen the ringer-relay is energized, the spring to `which the above magnets are connected is shifted, as was stated, away from the nongrounded'battery-spring to a second spring which is directly connected to ground. This connection to ground is between the releasemagnet and the winding of the differentialrelay that is in series with the rotary-linerelay, and, therefore, the private and release magnets are not included in the energizing-circuit of the calling subscribers transmitter. 1V hen an automatic and inanual` line are connected, if the differential-relay becomes active, the springs that are included in the ringer-relay-circuit are separated, and the said ringer-relay becomes Icle-energized, thereby restoring the releasemagnet and the other said magnets to the non-grounded pole of the battery. V1f this occurs while the rotary and vertical line-` relays are energized, the connector is then released. occur, as has `been explained, when the calling automatic subscriber restores his receiver. Not only is the differential-relay used as dead resistance for retardation means, and for intermediate means by which to release, but in the hands, so to speak, of the calling subscriber serves also yas an Andi this, in fact, is what does their Vcorresponding releasefar'inature.

lector, andV whenever the former is ener-` gized, because the connector-line-relays are energized srmultaneously, the bach-release-relay of said "irst-selectoi becomes energized at the same time.v Therefore,fboth the connector and the selector are released at 'onC-e. rtfi's by means of the'con nectoreback-release-relays that my iinprove'd connectors are released when their shaft-'wipers are rotatedk onto busy lines.l It isti-ue that'the'back-releaseerelay becomes energized when the calledl subscriber removes his receiver from its hook, but the energizing-current or the talking-circuit thus completed is too weak to operatively magnetize said relay. The normal-conductors that lead4 fromfthe cconnector-banks of my invention terininatefin thejacks of manual' exchange lines, lattercorrespond tov thelocation of the yterminals'of said normals in the connectori bank-sy from which Vthey lead". An automatic exchange subscriber in ringing a inan-A u'al exchange subscriber .eiiiploys the ring:- ingsgene-rator ofthey manual system, but this is not essential;` The ringing-.current passes' throughfthe` common vbattery at the manual'station which is connected to the manual cord-circuits on the side of the ansiiierilrig-'pllug Furthermore,in the descrip@ tion ofthe selector and connector it will 'beu' understoodV thaty the aperture 'on the Aen'd of the release-link is'ar enough trointhe end, so' that when said link is un-Y lock-eclfrom' the double-dog, and after the verticalarm falls back, the link will then rest .on` lthe'top of the double-'dog 'lug with whichit normally engages. Also, in Fig. 2,

the busyesignaling apparatusI shown is notl necessarilyof the particular type described, asany suitable apparatusV vfor that purpose will answer as well. In the drawings, the various release-magnets are illustrated as lia-ving only one coil, but this has been 'for the purpose ot simplifying .the illus tration'. In actual practice it is found that ai' release-magnet works better when composedv ot two coils both of which' constitute one magnet and which operate lupon In addition, the rotary and vertical pawls of the Adifferent switches, when they reach theV limit of their stroke, encounter a bumping post o-r guide-pin that directs the stroke of the pawl' in the proper direction, and at the same tiinelimits the movement so that theshatt'may not-be rotated toofar at each stroke. j f

1 With .my improved arrangement, it will be 'seenfthatthev multiple-'jacks allotted to the' numbers of which4 comingv calls-that is, ca'llsvsent out frein the manual exchange subscribers station, and" lcalls sent into such station by the manual switchboardoperator; and in addition, this same manualexchangesubscribers line is provided with va plurality of connector-bank-terminals" for use only in establishing connection with suoli subscribers line, and to be used only by automatic exchange subscribers in calling the manual exchange subscriber. Vhenl the connectorl7 makes connect-ion with the line-terminals allotted to the manual exchange subscribers line, the cut-oii-relay is energized by cur.n rent flowing tromthe battery B2 through a circuit including impedance coil 339, contacts 34:9 and 350 .ot the ringer-relay, the

shaft-wiper 312 and the bank-contact 311,

thevcondnctor 421' and the ground connections G54 and Howeverywhen' the subscriber at station .#:220v attempts to rin-g the belllfo't subscribervat station #620, the saidl ringer-relay is then cle-energized, and at such time .the cut-off-relay 55 isenergized by current flowing from the battery B1 over a circuit Aincludii'ig thev resistance 74, 'the conductor 429, -the contacts 350 and 351 o'l the ringer-relay .344, the conductor 421 and the ground connections G4' and G3. In this way, .the-said ringer-relay is adapted to shift the cu-t-o-relay 55 from one battery tothe other,-and Jfronrone energizing-circuittov the other, so that after the conhectorl has established its connection, the

saidcut-ott'relay `then remains energized regardless oi" whetherv the ringer-relay is energized i or cle-energized. Also, as will be seen, the differential-relay 329 is used by the calling subscriber at station #22() in ringing the bell at station #620, inasmuch as this diferentiabrelay controls the circuit of the ringer-'relay 344:, whereby the said ringer-relay is de-energized as soon as the diferentiahrelay is energized after the connection 'has been established with the called subscribers line.l In addition, the said differential-relay is used `by the calling subscriber at 'station #220 in releasing the different switches, after the two subscribers haveV terminated their' conversation, as by hanging up'A the receiver 100, and thereby momentarily usingv the ground for short# 

